Lawn edger with insulated handle

ABSTRACT

A device having a plug-in electrical cord for running a motor which drives a cutting blade. The device has an electrically conductive handle insulated against electrical spark jump from the motor and electrically insulated from the blade in the event the blade cuts the power cord. More specifically an edger-trimmer is described in which an insulating shaped barrier separates conductive portions of the motor and drive mounting frame from the handle and in which insulating elements space the guide plate, which is adjacent the blade, from the casing providing an airgap electrically isolating the guide plate from the conductive frame portions and from the handle of the device.

United States Patent [72] Inventor Michael T. Lay

West Chicago, Ill. (2| Appl. No. 842,596 [22] Filed July 17, I969 [45] Patented Dec. 14, 1971 [73] Assignee G. W. Murphy Industries, Inc.

[54] LAWN EDGER WITH INSULATED HANDLE Primary Examiner-William B. Penn Assistant Examiner-C. W. Hanor Attorney-Hofgren, Wegner, Allen, S'tellman & McCord ABSTRACT: A device having a plug-in electrical cord for running a motor which drives a cutting blade. The device has an electrically conductive handle insulated against electrical spark jump from the motor and electrically insulated from the blade in the event the blade cuts the power cord. More specifically an edger-trimmer is described in which an insulating shaped barrier separates conductive portions of the motor and drive mounting frame from the handle and in which insulating elements space the guide plate, which is adjacent the blade, from the casing providing an airgap electrically isolating the guide plate from the conductive frame portions and from the handle of the devicev Patented Dec. 14, 1971 3,627,054

2 Sheets-Sheet 1 J8 7/Zic %Qg .7 Z

Patented Dec. 14, 1971 2 Sheets-Sheet 2 LAWN IEDGlElit WITH INSULATED HANDLE BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to protection of an operator of an electrically driven cutting tool against electrical shock. More particularly the device relates to a lawn edger and trimmer device having an electrically conductive cutting blade and an electrically conductive metal handle both of which are electrically isolated from the motor and from each other to protect against shock in the event of any internal electrical malfunction or in the event the blade cuts either the electrical power supply cord or any other electrical conductor.

2. Brief Description of the Prior Art Edger'trimmers and other cutting tools are oftendriven by electric motors and an electrical power cord is used for providing electrical power for the motor. Many such tools have aluminum or other conductive frame portions and handles. The operator can receive shock from the handle either through spark jump from the motor or through malfunction of the motor. Additionally, blades of such cutting tools sometimes accidentally cut power supply cords either for their own power or for other power such as garden lights and the like and the blade or adjacent guide portion of the device can conduct electricity to the handle giving the operator a shock or to the motor causing extensive damage thereto.

SUMMARY OF THE INVENTION The present invention provides a cutting device such as a lawn edger and trimmer in which an electrically conductive handle is electrically isolated and insulated from receiving sparks from the motor and insulated from the blade to prevent shock to the operator in the event of any internal electrical malfunction or in the event the blade cuts any power supply cord.

While an illustrative embodiment of the invention is shown in the drawings and will be described in detail herein, the invention is susceptible of embodiment in many different forms and it should be understood that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of an edger-trimmer embodying the present invention;

FIG. 2 is an enlarged fragmentary section through the edger-trimmer of FIG. I along line 2-2 ofFIG.

FIG. 3 is an enlarged fragmentary section through the edger-trimmer along line 3-3 of FIG. 1;

FIG. 4 is a perspective view of an insulating body in the device of FIGS. 1 through 3; and

FIG. 5 is a fragmentary section through the device along line 5-5 of FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning first to FIG. 1, an embodiment of the edger and trimmer of this inventionis shown generally at 10. Edgertrimmer has a plastic casing 12 including a blade guard portion 13 for guarding a metal cutting blade 14 and a vented portion 16 containing an electric motor. Plastic casing 12 is supported on two rear wheels 18 and 20 (FIGS. 2 and 4) and a front wheel 22 which is preferably turned at an angle away from the blade during forward travel of the device in the manner described in my copending application, Ser. No. 842,597 A metal guide plate 24 is mounted on the plastic casing 12 for guiding along the edge of a sidewalk during lawn edging operation. During trimming operation, plate 24 protects against objects which may be thrown by blade 14.

A tubular metal handle 26 is connected to casing 12 through a pivotal connection as at 28, provided with a locking device 30. Pivotal connection 28 permits pivoting of the casing and blade between positions casing and blade between edger and tions. The locking device 30 secures either position. A preferred pivotal connection and locking device system is described in my c-opending application, Ser. No. 842,598.

The electric motor in vented casing portion 16 is mounted on an aluminum motor and drive train mounting frame 32 (FIGS. 2 and 3). The motor drive shaft 34 is mounted by a suitable bearing 36 mounted in frame 32 and shaft 34 has a toothed or gear end 38. Shaft end 36 is in mesh with a gear 40 on shaft 42 which is mounted by suitable bearings 41 and 43 for driving blade 14 through an electrically insulating slip clutch 44. A preferred form of slip clutch is described in my copending application, Ser. No. 842,602.

A fan blade 46 (FIG. 3) may be mounted on shaft 34 for drawing air in through vented housing portion 16 for cooling the motor and other internal parts. The isolated electric cord 46 for supplying electrical energy for the motor is contained within handle 26 and extends from handle 26 at the upper end thereof in a normal manner for plugging into a suitable electric outlet.

In operation of the device thus far shown, the motor is turned on by a suitable switch (not shown) adjacent the upper end of handle 26 and, in the position shown in FIGS. l and 3, the device is used for edging pavements such as sidewalk and the like. Plate 24 guides along an edge of the sidewalk in the manner shown in FIG. 1 while blade 14 rotates to dig and cut adjacent plate 24 to produce a neatly edged lawn along the pavement. The device can be converted to a trimmer for trimming around trees, shrubs, and the like, by loosening locking device 30 and rotating casing 12 clockwise 90 relative to handle 26 and wheels 18 and 20 as viewed in FIG. 1 and retightening locking device 30. Rear wheels 18 and 20 are part ofa carriage secured to handle 26 and which stays with handle 26 when the casing 12 is rotated. When operating as an edger, the angularly disposed front wheel 22 advantageously helps keep guide plate 24 against the edge of the sidewalk. When operating as a trimmer, front wheel 22, which is mounted on casing 12, is rendered inoperative since it has been moved 90 relative to wheels 18 and 20 with casing 12 and does not engage the ground. A scalp guard is provided on the blade guard 13 which engages the ground when the casing is in the trimmer position to prevent cutting into the ground during trimming.

A plurality of provisions are included to protect the operator against shock due to spark jump from the motor in the event of internal electrical malfunction or in the event of accidental cutting of the electric supply cord 48 by blade 14. The insulated clutch 44 blocks transmission of electricity from blade 14 to the remainder of the device. Should the cut cord engage guide plate 24, transmission of electricity to the device is blocked by plastic casing 12 and an airgap provided between plate 24 and casing 12 at the mounting position of casing 12. Further, insulating member 33 provided between the metal handle 26 and the motor and gear train mounting frame 32 blocks electrical conduction from frame 32 and prevents spark jump from the motor from reaching the metal handle 26.

Returning to the mounting of plate 24 and referring to FIGS. 2 and 3, screws 50 secure guide plate 24 to integral plastic projecting spacers 52 of casing 12. Screws 54 are spaced laterally from screws 50 and secure frame 32 in casing 12. The spacers 52 provide an airgap 56 between plate 24 and screws 54 for inhibiting spark jump from guide plate 24 to screws 54 in the event that guide plate 24 should come into contact with a cut power supply cord. Screws 50 are electrically insulated from frame 32 by plastic casing 12 and plastic spacers 52.

Referring to FIGS. 2, 4 and 5, the insulator member 33 is secured between aluminum frame 32. and a metal handle receiver frame 58 by female threaded insulating capnut and sleeve combinations 60 and metal screws 62. Receiver frame 58 is secured in an extension of casing 112 and receives hollow the casing and blade in' platform portion 68. Portions 66, 68, 70 and 72 metal handle 26 for pivotal movement in a cylindrical receiver portion of frame 58.

Insulator member 33 includes a foot portion 64 which extends below frame 32 and has its bottom portion blocking any spark jump from the lower portion of frame 32 to the lower portion of frame 58. A leg portion 66 extends upwardly from foot portion 64 and a platform portion 68 extends forwardly from the top or leg portion 66. A pair of separate spaced back portions 70 and 72 extend upwardly from the forward end of physically insulate frame 32 from frame 58. As best seen in FIGS. 4 and 5, wall portions 74 and 76 stand upwardly at the inside edges of back portions 70 and 72 and define a passageway therebetween for receiving insulating tube 63 from handle 26 which encases power line 48. Another wall portion 78 stands upwardly along the outer edge of back portion 72. Wall and back portions 72, 74 and 78 block any spark jump from the motor to the handle receiving frame 58 to further protect the operator from shock. A downwardly extending "L" shaped flange 80 is provided along each side of insulator member 33 at the lateral edges of leg portion 66 and platform 68 to further decrease the possibility of spark jump or electrical conduction from frame 32 to handle receiving frame 58.

I claim:

I. A cutting device comprising a casing including an electrically conductive frame portion, an electric motor mounted in said casing and driving a cutting blade, electrically conductive guide means adjacent said blade and mounted on said casing, a supply cord for supplying electrical energy to the motor, an electrically conductive handle secured to said casing, electrical insulating means insulating said handle from the guide means, insulating means insulating said handle from spark gap jump of sparks from the motor and electrically conductive handle mounting means securing the handle to the casing and wherein said insulating means comprises a mass of insulation including a foot portion underlying a portion of said handle mounting means, a leg portion extending upwardly and insulating the handle mounting means from the casing frame portion, a platform portion extending from the top of said leg portion horizontally underlying the handle mounting means and overlying the casing frame portion and back and sidewall portions upstanding from the platform edges insulating the handle from the casing and blocking spark gap jump from the motor.

2. The device of claim 1 wherein said insulating means comprises plural airgaps between the guide means and the frame portion.

3. The device of claim 2 including a plastic insulating wall for each airgap. 

1. A cutting device comprising a casing including an electrically conductive frame portion, an electric motor mounted in said casing and driving a cutting blade, electrically conductive guide means adjacent said blade and mounted on said casing, a supply cord for supplying electrical energy to the motor, an electrically conductive handle secured to said casing, electrical insulating means insulating said handle from the guide means, insulating means insulating said handle from spark gap jump of sparks from the motor and electrically conductive handle mounting means securing the handle to the casing and wherein said insulating means comprises a mass of insulation including a foot portion underlying a portion of said handle mounting means, a leg portion extending upwardly and insulating the handle mounting means from the casing frame portion, a platform portion extending from the top of said leg portion horizontally underlying the handle mounting means and overlying the casing frame portion and back and sidewall portions upstanding from the platform edges insulating the handle from the casing and blocking spark gap jump from the motor.
 2. The device of claim 1 wherein said insulating means comprises plural airgaps between the guide means and the frame portion.
 3. The device of Claim 2 including a plastic insulating wall for each airgap. 